Shock absorbing caster wheel



July 13, 1965 R. J. KINDLEY SHOCK ABSQRBING GAS'I'ER WHEEL Filed Jan. 26, 1965 INVENTOR.

Robert J. K/nd/ey Attorney United States Patent 3,194,293 SHOCK ABSORBING CASTER WHEEL Robert J. Kindley, Albuquerque, N. Mex., assignor, by

mesne assignments, to the United States of America as represented by the United States Atomic Energy Commission Filed Jan. 26, 1965, Ser. No. 429,946

. 1 Claim. (Cl. 152-327) This is a continuation-in-part of application Serial No. 236,172, filed November 7, 1962, now abandoned.

The present invention relates generally to caster-type wheels and more particularly to improved such wheels capable of absorbing or mitigating shock and other loads.

Commercially available shock absorbing caster wheels heretofore known employ shock mitigating systems such as spring arrangements, Belleville washers or rubber compression assemblies. These casters are usually provided with a pivoting wheel or horn assembly that rotates upon reception of a shock load for transmitting the load to the shock mitigating system employed. Thus, such casters suffer several shortcomings or disadvantages which tend to lessen their desirability in many applications; for example, these casters are relatively more complex and are normally somewhat heavier than conventional nonshock absorbing casters of the same size and capacity. Also, such casters must be made necessarily larger than the conventional casters in order to accommodate the shock absorbing or shock mitigating system.

The present invention aims to overcome or substantially minimize the aforementioned and other shortcomings and disadvantages of the heretofore known shock absorbing casters by employing a shock mitigating system commensurate with the loads involved and which is in as small and compact package as possible. It is therefore a principal object of the present invention to provide the caster wheel assembly with shock mitigating capabilities without relying on a tension or compression spring arrangement.

Another object of the present invention is to utilize an improved wheel with a rubber-like tire capable of stretching and deforming in shear to provide shock mitigation or shock absorption.

Another object of the present invention is to provide a cavity between a rubber-like tire and a wheel hub for receiving deformed portions of the tire.

A further object of the present invention is to provide the rubber-like tire with an anular ring of metal or other relatively rigid material for distributing loads more uniformly throughout the wheel and tire.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiments about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

Preferred embodiments of the invention have been chosen for purposes of illustration and description. The embodiments illustrated are not intended to be exhaustive nor to limit the invention to the precise forms disclosed. They are chosen and described in order to best explain the principles of the invention and their application in practical use to thereby enable others skilled in the art to best utilize the invention in various embodiments and modifications as are best adapted to the particular use contemplated.

In the accompanying drawing:

FIG. 1 is a fragmentary side elevational view, partly 3,194,293 Patented July 13, 1965 "ice cut away, of a wheel assembly showing one form of the present invention;

FIG. 2 is a sectional view taken along line 22 of FIG. 1;

FIG. 3 is a fragmentary sectional view showing another form of the present invention;

FIG. 4 is a fragmentary sectional view showing yet another form of the present invention; and

FIG. 5 is a fragmentary sectional view showing a further form of the present invention.

Referring in more detail to the drawings, the present invention is directed to a caster wheel assembly, generally indicated at 10, which comprises a metal hub 11 having adjacent opposite ends thereof a pair of laterally extending metal flanges 12 and 13. The hub 11 may be provided with an opening 14 therethrough for receiving a supporting shaft (not shown) which may be mounted therein by any suitable bearing structure or arrangement (not shown). The flanges 12 and 13 are annular in form and may be attached to the ends of the hub 11 in any suitable manner, for example, by a bolting arrangement 15, as best illustrated in FIG. 2, welding, or, if desired, by making the hub and the flanges as an integral piece, so as to form an annular groove or channel about the central portion of the hub 11 for receiving an annular rubber-like shock absorbing tire 16 therein. While flanges 12 and 13 are each shown bolted to the hub 11 it will be clear that either flange could be integral with the hub and the other bolted thereto. It may be desirable to provide openings through the flange walls to lighten the wheel assembly.

The shock absorbing tire 16, which is made of an elastomeric material, such as, for example, rubber, having a durometer hardness in the range of about 30 to 90, or a suitable yieldable plastic such as polyurethane, or the like, may be provided with a relatively thick cross-section capable of enjoying a preselected amount of yieldability while at the same time retaining its load supporting properties without excessive deformation. The tire 16 is placed into or formed within the annular channel in such a manner that opposite side faces of the tire each abut an inner surface of a particular flange; the forming could be by injection of the tire material between the flanges and the placing could be after preforming the tire or by building it up with wrapping and curing-these are merely some examples. The tire 16 is preferably bonded to the flanges or supports, or otherwise secured thereto in any other suitable similar manner, so as to prevent relative movement between the flanges and the tire at the interfaces thereof, and where appropriate the inner faces of the flanges would preliminarily coated with a bonding adhesive. The cross-section of the annular tire should be sufficiently thick so that the outer periphery or edge of the annular flanges 12 and 13 lies intermediate the inner and outer peripheries or edges of the tire. With the inner portion of the tire secured to the flanges, it may be desirable to provide the part of the tire extending outwardly beyond the edge of the flanges with an outwardly disposed converging configuration. Thus, as an impact or other load is applied to the outer edge or periphery of the tire 16 it is transmitted into the portion of the tire intermediate the flanges instead of being transmitted directly to the flanges by expanding the outer portion of the tire over the outer edges of the flanges.

When the tire 16 is subjected to a load, the elastomeric material deflects, causing it to stretch and deform in shear and thereby effectively absorb or mitigate the impact or other load. To facilitate such deformation, it has been found that by providing a cavity or volume 17 between the tire may readily deform thereinto to substantially I minimize the transmission of the impact or other load to the surrounding hub and flanges.

ing its deformation.

If desired, as mentioned above, the tire may be formed withincthe channel and bonded to the inner surfaces of the-flanges 12 :and 13. To achieve this result the hub: may be provided with a plurality of mold core openingstherethrough, such as indicated at 13 and then the channel 17 filled with molding sand to the cavity size or height,

desired, r The elastomeric material may then'be placed aboutrthe sand and otherwise molded'and vulcanized by ing the material in'the preferred shape while at the same timeeifectinga desirable bond betweenthe material and theinner surfaces of the flanges 12 and t3. It may be desirable to slightly roughen, by light sandblasting, acid, a or otherwise, theinnersurfaces of thefianges to enhance the bonding. After'complcting the above-mentioned vulcanizing the sand fill forming the cavity may be withdrawn therefrom through the openings 18 in the hub.

To enhance the load absorbing or shock mitigating action of the elastomeric material, itLis preferred to gradu-v ally slant or converge the inner walls of the flanges toward the central portion of thehubso that, as the elasto meric material deforms, thegradually converging flanges tend to compress and deflect the material inwardly to maintain it in shear.

The cavity or volume 17 may bevof any suitable size or dimension so long as it is capable of receiving the deformedmaterial Without excessively restrictingfthe. movement thereof, such as by permitting the material to engage the hub du'rusing in any suitable procedure which is capable offor'rn I in an upward direction and to similarly movethe ring,

to ,thus cause material adjacent the ring to stretch in shear throughout thezentire circumference of the ring and '1' tir e; Thus the loading is distributed about the entire circumferential area of the elastomeric material adjacent to the ring. The ring is'preferably secured to the elasthe surface of the ring as mentioned hereinabove or to i place several openings through the sides thereof so as to' enhance therbonding and grip betweenthe ring and the material. 7 r While the annular ring may beof any siutable configuration a preferable form is a T-shaped arrangement as;

shown in;FIG. 2. The T-shaped ring generally indicated of the tire 16 to a location in the material beyond the ps 1 riphery ofthefla'nges, so that it effectively"ov erlaps the contacting area the, stretching actionby the ring on the of the tire.

is essentially confined to an area betweenthe flanges so latter. The relatively large'area of the material engaged 3 by the ring is advantageous inthat with such 'a large:

- The crossarm 22 of the T-shaped ring 20 maybe posibe possible with just the stenrZll alone.- It is preferred that the maximumhorizontaldimension ofcrossar m 2 2; 7

- should not bev substantially greater than about'one-thirdj I Tithe spacing betweenflangesllrjand 13's'o i aSvtQpIOVided a large area ofunobstructed elastom'eric'materialbetween the crossarm and flanges-.which will'n'ot bedamag ed by l thecrossarmitself. l f a While :the above described-ringarrangement,is'parj i ticularly, advantageous for applications in whichthe caster -wheel may be subjected to heavy *loads, there may beg other instancesv ingwhich the casterfapplication 'is l notz as critical, thus ,permit ting the use of simpler ring' con figurations, for; example such as saw/arms. '3Jand v4. 7 j i With reference to the ring arrangements shown-inrFIGSf ,i f r 3 and 4, the rings 24 and 25 respectivelygfunction in a manner similar to the stem 21? {of iring 20: (FIGS- 2) in 7 their ,elastomeric jmaterial st'retchingj capabilitiesgjln the A ring arrangement shown in'EIG. 4,-the ting g5 bisects the? g 1 tire16'so as to enable, if desired; the'embeddingi of the. a a ring in the materialjto be attained' byaEdifferentand in: some instances a-less expensive procedure; -for*exampl e," v the tire 16 "may be initially formedfl-in twqseparate *a'n-f: nular sections, each ofgwhich may then be securely bonded;

to the ring by a suitable adhesive or'thc lik r:

Theformillustratedrin FIGgSgisjditectd'to a caster: wheel'assembly which does not utilizean "annular" rigid 1 5 ring, but which does haveiside faces-of tire and fflanges securely bonded to each other in the: manner previously noted. While such'an arrangementmay beiconsidered less desirablethan the ring-containing, assemblies, it may between tire side faces and the flangeszy l The load deflection characteristics 'of1theishockab5', I sorbing wheels' set forthabove maybe variedtoibe adapt r i able to the particulariusecontemplated. by'su'ch selective-i" 7 1y changeable factors as thetype,'yieldability :anddurbm eter hardness of theelastomeric material, the'width -of thertire'betweenthe flanges,- thethicknessiand the. diarna eterofthe tire; the:area of the tire-bonded tontheflanges,

and the size; width and configur'ation of the annular ring.

*It will be; seen that-thepresent invention sets forth novel caster wheel 1 assemblie's' whichiare capable; of providing I 7 shock or load absorbingor mitigatingpropertiessuperior; I V to the conventional; heretofore known larger; and more complex shock absorbing casters} The caster.. wheels 'of j V the present invention, particularly?assembliesicont aining the annular ring, are capable of protectingfor example} a dolly and its contents from impacttl'oadsdevelopedby a free-fall to a hard surface {SUQhvfiSi concrete, blacktop 201 wood floors. By way, ,ofexampleyin' ,one particularin-j r stance a twelve inch ifree fall wasnicely absorbed 7 As various changes'rrnay bemade in th'elfo rm, cassette tion and arrangement of the partsfhereinwithoutdepart i V ing from thespirit and scope ofrthe inventionandiwith that all matter. herein is to and not in a'lirniting sense.

I claim:

f 'A shock absorbing-caster. wheelcomprising"the'com biuation' of a hub,'a pair of; spaced apartfiangescarried by said hub and projecting laterally therefrom and ternii-; nating in peripheral portions spaced radially from said I hub, a single centrally apertured rigid disciwitha widened rim portion at the outermost extremity thereof spaced intermediate 'andcentrally disposed with f respecttosaid fianges and generally parallehthereto withthe :innerspe-Q riphery of the disc spaced radially from said hub and Withthe major portionz comprising'fabout gtwo thirds' of 7' 1 the radial Widthof-said'disc exclusive of said rim portion f r i positioned radially inwardly withgrespect :to: and ioverlapped by said peripheral portions of theflanges, and only} a minor portion comprisingabout one-third-gofftheradial width exclusive of said rim portion disposed outwardly of said peripheral portions, the maximum horizontal dimensions of said rim portion being not substantially greater than about one-third the spacing between said flanges, and a rubber-like mass of material spaced from said hub filling the spaces between adjacent faces of said flan es and intermediate disc completely embedding said disc except at its innermost periphery and fixedly secured directly to said faces buttressing said disc against substantial movement away from said parallel disposition and assuring that deformation of the rubber-like material by said disc is in shear and is achieved in the mass portions between the flanges.

References Cited by the Examiner UNETED STATES PATENTS 1,182,297 5/16 Morris 15248 1,402,191 1/22 Thiele 1645 2,393,161 1/46 Haushalter 152325 3,114,408 12/63 Ross 152-323 FOREIGN PATENTS 447,821 4/48 Canada. 534,136 2/41 Great Britain.

ARTHUR L. LA POINT, Primary Examiner. 

